The present invention generally relates to recording and reproducing apparatus and, more particularly, to apparatus that is adapted to record and reproduce television signals, using digital techniques.
The continued advances in technology have resulted in many changes in the equipment that is currently being used in television broadcast stations. One of the more recent changes that has evolved is the shift away from photographic techniques toward the use of magnetic media in many phases of the operation of the commercial broadcast television station. For example, feature films being broadcast often originate from magnetic tape rather than film and television station news departments are increasingly converting to videotape recording systems rather than using film cameras to provide the visual coverage of the news stories. Moreover, many systems utilize travelling transmitters that can either broadcast on location coverage or transmit such coverage to the station which can either be broadcast "live" or videotaped, edited and broadcast at a later time. Some of the many benefits of these techniques are the ease of handling, flexibility and speed of processing compared to the use of photographic film, coupled with the ability to reuse the magnetic tape when the information that is recorded on them is no longer needed.
One of the last remaining film domains in the present day commercial television broadcasting station is the Telecine island which uses 35 millimeter film transparencies. The Telecine island is used to provide video still images that are used during programming, commercials, news and the like, i.e., wherever a still image may be used during operation. Their use is extensive as is evidenced by the fact that the average commercial broadcast television station maintains a total gile on the order of about 2000 to 5000 35 millimeter transparency slides. The maintenance of the total file represents a laborious operation which requires introduction of new slides, the discarding of obsolete slides and the maintenance of an accurate index so that they can be readily obtained when needed. When slide program sequences are to be assembled, they must be manually carried to the Telecine island, cleaned and manually loaded. Even with the cleaning operation, dust particles and scratches and the like may easily result in an unsatisfactory end product even when the projectionist is careful. Moreover, following their use during broadcasting, the slides must be removed and returned to the file. The entire assembling, use and refiling of the slides represent a substantial labor investment because of the many manual operations that are required. The Telecine operation is considered to be one of the most antiquated operations in many modern broadcast stations and is basically incompatible with a fully automated station operation.
In contrast to the Telecine island or the use of opaque graphic material as the source for generating video still images, the apparatus described herein involves a recording and playback apparatus that will record and reproduce still images, with the still image video information being stored on magnetic media. The apparatus utilizes generally standard computer disc drives (though modified in some respects as will be described) as the magnetic storage media and thereby eliminates the many problems that are associated with slide transparencies. Since the still images are recorded on magnetic media, the problems of physical degradation during use, e.g., dust particles and scratches, are not experienced. Moreover, since the recorded information can be easily accessed, the same still image may be used by operators at different locations almost simultaneously.
As will be described in detail herein, the video information for the still images is recorded in parallel on a plurality of surfaces of the disc pack of the disc drive, with a frame of video information being recorded at each separate radial location or track on the disc pack. With standard disc packs, there are a total of about 815 tracks upon which information can be recorded and, in the illustrated embodiment, each still image is recorded on a track by recording one field on one set of surfaces during one revolution of the disc pack and the second field of the frame on another set of surfaces at the same radial location. Since the still images recorded on the tracks may comprise a relatively permanent library of a commercial broadcast television station, for example, it is therefore desirable that the information be protected from inadvertent or unauthorized erasure or overrecording by operators located at any of the various control stations which can control the recording and reproducing apparatus. On the other hand, it is desirable that other operations such as compiling sequences of still images for use during broadcasting and the like be carried out without substantial restriction.
For this reason, the apparatus of the present invention specifies certain of the tracks as being bulk tracks and others as working tracks and prohibits certain operations from being performed with respect to these classifications of tracks. In the illustrated embodiment, the vast majority of the 815 tracks are specified as bulk tracks and only a total of 64 tracks are specified as working tracks. The working tracks can be used to record and reproduce still frames generally without significant restriction.
However, with respect to the bulk tracks, the apparatus of the present invention prohibits erasure or overrecording thereon in the absence of an enabling signal being produced and the enabling signal is provided by a switch that has a key lock switch or other comparable security switch. Thus, only certain authorized personnel are able to operate the switch and they are able to control the erasure or overrecording of information that is recorded on the bulk tracks. Operators can compile a sequence of still images on the working tracks for subsequent use during programming, for example, and the apparatus of the present invention also prohibits the destruction of the entire sequence in the absence of the enabling signal (one mode of operation of the machine permitting an entire sequence to be erased by carrying out a single set of instructions).